1. Field of Invention
The present invention generally relates to memory technology. More particularly, the present invention relates to non-volatile magnetic memory.
2. Description of Related Art
Magnetoresistive random access memory (MRAM) is a type of non-volatile memory with fast programming time and high density. An MRAM cell of giant magnetoresistance (GMR) has two magnetic layers separated by a nonmagnetic conducting layer. Information is stored as directions of magnetization vectors in the two magnetic layers.
The resistance of the nonmagnetic conducting layer between the two magnetic layers indicates a minimum value when the magnetization vectors of the two magnetic layers point in substantially the same direction. On the other hand, the resistance of the nonmagnetic conducting layer between the two magnetic layers indicates a maximum value when the magnetization vectors of the two magnetic layers point in substantially opposite directions. Accordingly, a detection of changes in resistance allows information being stored in the MRAM.
In the conventional standard MRAM structural design, an MRAM bit lies between a pair of word lines arranged at right angles to each other, above and below the MRAM bit. A magnetic field is generated when current flows along the word line. Usually, a fairly substantial current is required to generate the magnetic field to control a dipole of the corresponding magnetic layer, which results in higher power consumption.
For the foregoing reason, there is a need for developing a method and a structure to reduce a current required for the word line, which controls a dipole of the magnetic layer.